The invention relates generally to a system for monitoring a relative displacement of components and more particularly, to a system for monitoring a relative displacement of end-winding components of a generator.
Rotating machines such as electric generators driven by steam turbines or gas turbines have the capacity to carry several thousand amperes of current in their stator windings. Stator windings generally comprise conductive bars secured in corresponding slots in a stator core and end windings extending beyond the stator core. End-winding components are subject to electro-dynamic and mechanical forces that induce a displacement of the end windings. Electro-dynamic forces are induced, for example, by large current passing through the end windings during starting and peak load conditions. Mechanical forces are caused by normal mechanical thermal expansion and vibrations of the rotating machine. It has been recognized that an excessive displacement of the end windings has several undesirable effects including that the winding insulation in the end windings may be destroyed leading to dielectric breakdown between end windings, and end windings may suffer from wear due to electromechanical forces that lead to premature failure of the rotating machine. There is a need in the art to monitor the end winding status, and an early and accurate detection of end winding loosening is desirable.
Conventional systems have been proposed, to detect the displacement of end winding components. However, electronic based systems have metal components that cannot be used near end winding components due to the high electro-magnetic fields, and optical vibration measurement systems are too expensive for cost effective use. Thus, it would be advantageous to provide a monitoring system which addresses these shortcomings.